Femto cells—building-based wireless access points interfaced with a wired broadband network—are generally deployed to improve indoor wireless coverage, and to offload a mobility radio access network (RAN) operated by a wireless service provider. Improved indoor coverage includes stronger signal and improved reception (e.g., voice or sound), ease of session or call initiation, and session or call retention as well. Offloading a RAN reduces operational and transport costs for the service provider since a lesser number of end users utilizes over-the-air radio resources (e.g., radio frequency channels), which are typically limited.
Coverage of a femto cell, or femto access point (AP), is generally intended to be confined within the bounds of an indoor compound (e.g., a residential or commercial building) in order to mitigate interference among mobile stations covered by a macro cell and terminals covered by the femto AP. Additionally, confined coverage can reduce cross-talk among terminals serviced by disparate, neighboring femto cells as well. Femto cells typically operate in licensed portions of the electromagnetic spectrum, and generally offer plug-and-play installation; e.g., automatic configuration of femto AP subsequent to femto cell subscriber registration with a service provider. Coverage improvements via femto cells can also mitigate customer attrition as long as a favorable subscriber perception regarding voice coverage and other data services with substantive delay sensitivity is attained. In addition, a richer variety of wireless voice and data services can be offered to customers via a femto cell since such service offerings do not rely primarily on mobility RAN resources.
Regardless the foregoing advantages provided by femto cells, typical operational designs of a femto cell access points generally lead to the following issues. (i) Unnecessary interference to femto cell subscribers in surrounding femto cells, and macro network end users as well, with ensuing reduction in overall network capacity; (ii) unnecessary signaling with nearby handsets unsuccessfully attempting to attach to femto access point(s), which results in a reduction of mobile station battery life; and (iii) additional complexity associated with macro-to-femto handover process.